Silane-modified biopolymeric, biooligomeric, oxidic or siliceous filler, process for its production and its use

ABSTRACT

Silane-modified biopolymeric, biooligomeric, oxidic or siliceous filler obtainable by reacting at least one biopolymeric, biooligomeric, oxidic or siliceous filler in a compressed gas with at least one silane. The silane-modified biopolymeric, biooligomeric, oxidic or siliceous fillers are used in rubber compounds.

This application is a Continuation of U.S. application Ser. No.10/140,041, filed on May 8, 2002, now U.S. Pat. No. 6,893,495.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a silane-modified biopolymeric,biooligomeric, oxidic or siliceous filler, a process for its productionand its use.

2. Description of the Background

The treatment of oxidic or siliceous compounds with organosiliconcompounds in order by means of this treatment to strengthen the bondbetween the inorganic filler and the organic polymer used infiller-reinforced elastomers, and hence to improve the properties of thefillers in the polymers, is known.

It is known from DE 2141159, DE 2212239 and U.S. Pat. No. 3,978,103 thatsulfur-containing organosilicon compounds such asbis(3-triethoxysilylpropyl) tetrasulfane or3-mercaptopropyltriethoxysilane are used as silane bonding agent orreinforcing filler in oxidically filled rubber compounds, for tiretreads and other automotive tire components among other things.

The use of mercaptosilanes in rubber compounds for tire treads is knownfrom FR-A 152.094.859.

In order to circumvent the considerable problems in the processing ofmercaptosilanes, such as pre-scorch, scorch and plasticity propertiesfor example, polysulfidic organosilanes such as e.g.bis(3-triethoxysilylpropyl) tetrasulfane or bis(3-triethoxysilylpropyl)disulfane (DE 2542534, DE 2405758, DE 19541404, DE 19734295) are mostlyused as a coupling agent for tire components, representing a compromisefor silica-filled vulcanisates in terms of vulcanisation safety, ease ofproduction and reinforcing performance.

The corresponding additives, especially the organosilanes and theunmodified fillers, can be introduced into the unvulcanised polymerblends in various ways.

The in-situ method involves a combined mixing process for fillers, suchas carbon black and silica, organosilanes and polymer.

The ex-situ method involves modifying the filler with the correspondingorganosilane or combining a mixture of various organosilanes beforemixing the filler with the polymer.

It is known that the filler surface can be modified by dissolving theorganosilicon compound in an organic solvent with subsequent treatmentof fillers, e.g. clays (U.S. Pat. No. 3,227,675).

Liquid addition (U.S. Pat. No. 3,997,356) or addition of the activefiller by means of a pre-produced physical blend of organosilane andfiller (DE 3314742, U.S. Pat. No. 4,076,550) is particularly importanttoday. The disadvantages of these blends, which do not undergo anythermal pretreatment, lie in their storage stability and hence in thestability of the product properties.

U.S. Pat. No. 4,151,154 describes oxidic siliceous fillers, the surfaceof which undergoes treatment with two different types of organosiliconcompounds. The oxidic particles are treated in such a way that theyexhibit a greater affinity to water and can also be more easilydispersed in aqueous systems.

The modification of kaolin suspended in water with various silanes isknown from U.S. Pat. No. 3,567,680. The organosilicon compounds that aredescribed are water-soluble in the quantities required for themodification, however, which means that in this case the filler can betreated from an aqueous solution.

U.S. Pat. No. 4,044,037 describes aryl polysulfides and mineral fillerstreated with these compounds, which are used in rubber compounds. Theyare produced in an aqueous/alcoholic formulation containing 99.9 to 80wt. % alcohol.

Moreover, a process in which the surface of siliceous fillers ismodified with the aid of an aqueous emulsion of water-insolubleorganosilicon compounds is known from EP-PS 01 26 871.

The known fillers modified ex situ with silane have the disadvantagethat the dynamic rubber properties tend to be worse rather than the sameas or better than those of fillers and silanes mixed together in situ.In the case of fillers with a large specific surface area or a raisedsurface texture, impregnation is not homogenous but instead is mostlyconfined to a thin surface layer and is therefore unsatisfactory.

The known methods for modifying fillers for rubber and plasticapplications with surface-active silanes or mixtures thereof are basedon the use of water, organic solvents or the direct spraying of theorganosilicon compound onto the surface of the filler with a subsequentconditioning reaction. The water-insoluble, rubber-typical silanes canonly be converted into hydrocarbon-based solvents, which are generallytoxic and highly flammable.

Accordingly, there remains a need for silane-modified fillers whichovercome these disadvantages.

SUMMARY OF THE INVENTION

It is an object of the present invention to produce a silane-modifiedbiopolymeric, biooligomeric, oxidic or siliceous filler which displaysan improved coverage of the surface with the correspondingrubber-reactive silanes and which therefore has comparable dynamicproperties in rubber to known silane-filler blends produced in situ anddisplays better dynamic properties in rubber than known silane-fillerblends produced ex situ.

Another object of the present invention is to provide a process for themodification of biopolymeric, biooligomeric, oxidic or siliceous fillerswith silanes, in which the modification reaction is not performed inwater or an organic solvent.

The objects of the present invention, and others, may be accomplishedwith a silane-modified biopolymeric, biooligomeric, oxidic or siliceousfiller obtainable by reacting at least one biopolymeric, biooligomeric,oxidic or siliceous filler in a compressed gas with at least one silane.

The objects of the invention may also be accomplished with a process forthe production of the silane-modified biopolymeric, biooligomeric,oxidic or siliceous filler according to claim 1, comprising reacting atleast one biopolymeric, biooligomeric, oxidic or siliceous filler in acompressed gas with at least one silane.

The objects of the invention may also be accomplished with a rubbercompound, which comprises a rubber and the silane-modified biopolymeric,biooligomeric, oxidic or siliceous filler described above.

The objects of the invention may also be accomplished with a rubbercompound, which comprises a rubber and the silane-modified biopolymeric,biooligomeric, oxidic or siliceous filler described above.

The objects of the invention may also be accomplished with a method ofproducing a molded part, comprising molding the rubber compounddescribed above into a molded part.

The objects of the invention may also be accomplished with a method ofproducing a article selected from the group consisting of pneumatictires for cars and lorries, tire treads for cars and lorries, tirecomponents for cars and lorries, cable sheaths, tubes, drive belts,conveyor belts, roll coverings, bicycle and motorcycle tires andcomponents thereof, shoe soles, sealing rings, profiles and dampingelements, comprising incorporating the rubber compound described aboveinto the article.

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following Figures in conjunction with thedetailed description below.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides a silane-modified biopolymeric, biooligomeric,oxidic or siliceous filler obtainable by reacting at least onebiopolymeric, biooligomeric, oxidic or siliceous filler in a compressedgas with at least one silane. The silane-modified biopolymeric,biooligomeric, oxidic or siliceous filler can have a BET surface area ofbetween 0.5 m²/g and 500 m²/g, preferably between 5 and 250 m²/g. Theseranges include all specific values and subranges therebetween, such as1, 2, 10, 25, 50, 100 and 300 m²/g.

The silane-modified biopolymeric, biooligomeric, oxidic or siliceousfiller can contain between 0.1 and 50.0 wt. %, preferably between 1.0and 25.0 wt. %, particularly preferably between 1.0 and 9.0 wt. %,silane. These ranges include all specific values and subrangestherebetween, such as 0.5, 2, 5, 10, 15, 30 and 40 wt. %.

The silane can be chemically and/or physically bonded to the surface ofthe fillers.

The invention also provides a process for the production of asilane-modified biopolymeric, biooligomeric, oxidic or siliceous filler,wherein at least one biopolymeric, biooligomeric, oxidic or siliceousfiller is reacted in a compressed gas with at least one silane.

An organosilicon compound having the general formula (I)Z-A-S_(x)-A-Z  (I)can be used as the silane, in which

-   x is a number from 1 to 12, preferably 1 to 8, particularly    preferably 2 to 6,-   Z is equal to SiX¹X²X³ and-   X¹, X², X³ can each mutually independently denote hydrogen (—H),    halogen or hydroxy (—OH),-   an alkyl substituent, preferably methyl or ethyl,-   alkenyl acid substituent, for example acetoxy R—(C═O)O—,-   or a substituted alkyl or alkenyl acid substituent, for example    oximato R¹ ₂C═NO—,-   a linear or branched hydrocarbon chain with 1–6 carbon atoms,-   a cycloalkyl radical with 5–12 carbon atoms,-   a benzyl radical or a halogen- or alkyl-substituted phenyl radical,-   alkoxy groups, preferably (C₁–C₄) alkoxy, particularly preferably    methoxy or ethoxy, with linear or branched hydrocarbon chains with    (C₁₋₆) atoms,-   a cycloalkoxy group with (C₅₋₁₂) atoms,-   a halogen- or alkyl-substituted phenoxy group or-   a benzyloxy group,-   A is a (C₁–C₁₆), preferably (C₁–C₄), branched or unbranched,    saturated or unsaturated, aliphatic, aromatic or mixed    aliphatic/aromatic divalent hydrocarbon group.

The group A can be linear or branched and can contain saturated as wellas unsaturated bonds. A can be provided with a wide variety ofsubstituents, such as e.g. —CN, halogens, for example —Cl, —Br or —F,—OH, alkoxides —OR¹ or —O—(C═O)—R¹. CH₂, CH₂CH₂, CH₂CH₂CH₂, CH₂CH(CH₃),CH₂CH₂CH₂CH₂, CH₂CH₂CH(CH₃), CH₂CH(CH₃)CH₂, CH₂CH₂CH₂CH₂CH₂,CH₂CH(CH₃)CH₂CH₂, CH₂CH₂CH(CH₃)CH₂, CH(CH₃)CH₂CH(CH₃) orCH₂CH(CH₃)CH(CH₃) can preferably be used as A.

The following compounds can for example be used as silane having thegeneral formula (I):

-   [(MeO)₃Si(CH₂)₃]₂S, [(MeO)₃Si(CH₂)₃]₂S₂, [(MeO)₃Si(CH₂)₃]₂ S₃,    [(MeO)₃Si(CH₂)₃]₂S₄,-   [(MeO)₃Si(CH₂)₃]₂S₅, [(MeO)₃Si(CH₂)₃]₂S₆, [(MeO)₃Si(CH₂)₃]₂S₇,    [(MeO)₃Si(CH₂)₃]₂S₈,-   [(MeO)₃Si(CH₂)₃]₂S₉, [(MeO)₃Si(CH₂)₃]₂S₁₀, [(MeO)₃Si(CH₂)₃]₂S₁₁,    [(MeO)₃Si(CH₂)₃]₂S₁₂,-   [(MeO)₃Si(CH₂)₃]₂S, [(EtO)₃Si(CH₂)₃]₂S₂, [(EtO)₃Si(CH₂)₃]₂S₃,    [(EtO)₃Si(CH₂)₃]₂S₄,-   [(EtO)₃Si(CH₂)₃]₂S₅, [(EtO)₃Si(CH₂)₃]₂S₆, [(EtO)₃Si(CH₂)₃]₂S₇,    [(EtO)₃Si(CH₂ ₃]₂S₈,-   [(EtO)₃Si(CH₂)₃]₂S₉, [(EtO)₃Si(CH₂)₃]₂S₁₀, [(EtO)₃Si(CH₂)₃]₂S₁₁,    [(EtO)₃Si(CH₂)₃]₂S₁₂,-   [(C₃H₇O)₃Si(CH₂)₃]₂S, [(C₃H₇O)₃Si(CH₂)₃]S₂S₂, [(C₃H₇O)₃Si(CH₂)₃]₂S₃,-   [(C₃H₇O)₃Si(CH₂)₃]₂S₄, [(C₃H₇O)₃Si(CH₂)₃]₂S₅, [(C₃H₇O)₃Si(CH₂)₃]₂S₆,-   [(C₃H₇O)₃Si(CH₂)₃]₂S₇, [(C₃H₇O)₃Si(CH₂)₃]₂S₈, [(C₃H₇O)₃Si(CH₂)₃]₂S₉,-   [(C₃H₇O)₃Si(CH₂)₃]₂S₁₀, [(C₃H₇O)₃Si(CH₂)₃]₂S₁₁ or    [(C₃H₇O)₃Si(CH₂)₃]₂S₁₂.

Compounds described in DE 198 44 607 (incorporated herein by reference)can also be used as the silane.

An organosilicon compound having the general formula (II)X¹X²X³Si-A-S—SiR¹R²R³  (II)can be used as the silane, in which

-   X¹, X², X³ and A mutually independently have the same meaning as in    formula (I),-   R¹, R², R³ are each mutually independent and denote-   (C₁–C₁₆) alkyl, preferably (C₁–C₄) alkyl, particularly preferably    methyl and ethyl,-   (C₁–C₁₆) alkoxy, preferably (C₁–C₄) alkoxy, particularly preferably    methoxy and ethoxy,-   (C₁–C₁₆) haloalkyl, aryl, (C₇–C₁₆) aralkyl, H, halogen or    X¹X²X³Si-A-S—.

The following compounds can for example be used as the silane having thegeneral formula (II):

-   (EtO)₃—Si—(CH₂)₃—S—Si(CH₃)₃, [(EtO)₃—Si—(CH₂)₃—S]₂Si(CH₃)₂,    [(EtO)₃—Si—(CH₂)₃—S]₃Si(CH₃),-   [(EtO)₃—Si—(CH₂)₃—S]₂Si(OEt)₂, [(EtO)₃—Si—(CH₂)₃—S]₄Si,    (EtO)₃—Si—(CH₂)₃—S—Si(OEt)₃,-   (MeO)₃—Si—(CH₂)₃—S—Si(C₂H₅)₃, [(MeO)₃—Si—(CH₂)₃—S]₂Si(C₂H₅)₂,    [MeO)₃—Si—-   (CH₂)₃—S]₃Si(CH₃), [MeO)₃—Si—(CH₂)₃—S]₂Si(OMe)₂,    [(MeO)₃—Si—(CH₂)₃—S]₄Si,-   (MeO)₃—Si—(CH₂)₃—S—Si(OMe)₃, (EtO)₃—Si—(CH₂)₂—CH(CH₃)—S—Si(CH₃)₃,-   (EtO)₃—Si—(CH₂)₂—CH(CH₃)—S—Si(C₂H₅)₃,    (EtO)₃—Si—(CH₂)₂—CH(CH₃)—S—Si(C₆H₅)₃ or-   (EtO)₃—Si—(CH₂)₂(p-C₆H₄)—S—Si(CH₃)₃.

An organosilicon compound having the general formula (III)X¹X²X³Si-Alk  (III)can be used as the silane, in which

-   X¹, X², X³ each mutually independently have the same meaning as in    formula (I) and-   Alk is a straight-chain, branched or cyclic (C₁–C₁₈) alkyl, for    example methyl, ethyl, n-propyl, n-butyl, n-pentyl, n-hexyl,    isopropyl or tert-butyl,-   (C₁–C₅) alkoxy, for example methoxy, ethoxy, propoxy, butoxy,    isopropoxy, isobutoxy or pentoxy,-   halogen, for example fluorine, chlorine, bromine or iodine,-   hydroxy, thiol, nitrile, (C₁–C₄) haloalkyl, —NO₂, (C₁–C₈) thioalkyl,    —NH₂, —NHR¹, —NR¹R², alkenyl, allyl, vinyl, aryl or (C₇–C₁₆)    aralkyl.

The term alkenyl can include the vinyl group as well as straight-chain,branched or cyclic fragments, which can contain one or more carbondouble bonds.

The term cyclic alkyl or alkenyl fragments can include both monocyclicand bicyclic or polycyclic structures, and cyclic structures providedwith alkyl substituents, for example norbornyl, norbornenyl,ethylnorbornyl, ethylnorbornenyl, ethylcyclohexyl, ethylcyclohexenyl orcyclohexylcyclohexyl groups.

Aryl can refer to phenyls, biphenyls or other benzenoid compounds, whichare optionally substituted with (C₁–C₃) alkyl, (C₁–C₃) alkoxy, halogen,hydroxy or hetero atoms, such as NR¹R²OR¹, PR¹R²R³, SH or SR¹.

Aralkyls can be the aryls listed above, which can be bonded to thecorresponding silicon atom or sulfur atom or to both by a (C₁–C₆) alkylchain, which in turn can be substituted with (C₁–C₃) alkyl, (C₁–C₃)alkoxy or halogen. If the aryl group has a hetero atom such as O or S,the (C₁–C₆) alkyl chain can also be bonded to the silicon atom and/orthe sulfur atom via the hetero atom.

The following compounds can for example be used as the silane having thegeneral formula (III):

-   (EtO)₃—Si—(CH₂)₃—H, (MeO)₃—Si—(CH₂)₃—H, (EtO)₃—Si—(CH₂)₈—H,    (MeO)₃—Si—(CH₂)₈—H,-   (EtO)₃—Si—(CH₂)₁₆—H, (MeO)₃—Si—(CH₂)₁₆—H, (Me)₃Si—(OMe),    ((Et)₃Si—(OMe),-   (C₃H₇)₃Si—(OMe), (C₆H₅)₃Si—(OMe), (Me)₃Si—(OEt), ((Et)₃Si—(OEt),    (C₃H₇)₃Si—(OEt),-   (C₆H₅)₃Si—(OEt), (Me)₃Si—(OC₃H₇), ((Et)₃Si—(OC₃H₇),    (C₃H₇)₃Si—(OC₃H₇),-   (C₆H₅)₃Si—(OC₃H₇), (Me)₃SiCl, ((Et)₃SiCl, (C₃H₇)₃SiCl, (C₆H₅)₃SiCl,    Cl₃—Si—CH₂—CH═CH₂,-   (MeO)₃—Si—CH₂—CH═CH₂, (EtO)₃—Si—CH₂—CH═CH₂, Cl₃—Si—CH═CH₂,    (MeO)₃Si—CH═CH₂ or-   (EtO)₃—Si—CH═CH₂.

An organosilicon compound having the general formulae (IV) or (V)[[ROC(═O))_(p)-(G)_(j)]_(k)-Y—S]_(r)-G-(SiX¹X²X³)_(s)  (IV)[(X¹X²X³Si)_(q)-G]_(a)-[Y-[S-G-SiX¹X²X³]_(b)]_(c)  (V)can be used as the silane,

-   in which Y represents a polyvalent species (Q)_(z)D(=E), whereby the    following applies:-   p is 0 to 5, r is 1 to 3, z is 0 to 2, q is 0 to 6, a is 0 to 7, b    is 1 to 3, j is 0 to 1, but if p=1 it can also commonly be 0, c is 1    to 6, preferably 1 to 4, t is 0 to 5, s is 1 to 3, k is 1 to 2, on    condition that-   (1) if (D) is a carbon, sulfur or sulfonyl, a+b=2 and k=1,-   (2) if (D) is a phosphorus atom, a+b=3 as long as c≧1 and b=1,    whereby a=c+1,-   (3) if (D) is a phosphorus atom, k=2,-   Y represents a polyvalent species (Q)_(z)D(=E), preferably —C(═NR)—,    —SC(═NR)—, —SC(═O)—, (—NR)C(═O)—, (—NR)C(═S)—, —OC(═O)—, —OC(═S)—,    —C(═O)—, —SC(═S)—, —C(═S)—, —S(═O)—, —-   S(═O)₂—, —OS(═O)₂—, (—NR)S(═O)₂—, —SS(═O)—, —OS(═O)—, (NR)S(═O)—,    —SS(═O)₂—,-   (—S)₂P(═O)—, —(—S)P(═O)—, —P(═O)(−)₂, (—S)₂P(═S)—, —(—S)P(═S)—,    —P(═S)(−)₂, (—NR)₂P(═O)—,-   (—NR)(—S)P(═O)—, (—O)(—NR)P(═O)—, (—O)(—S)P(═O)—, (—O)₂P(═O)—,    —(—O)P(═O)—,-   —(—NR)P(═O)—, (—NR)₂P(═S)—, (—NR)(—S)P(═S)—, (—O)(—NR)P(═S)—,    (—O)(—S)P(═S)—,-   (—O)₂P(═S)—, —(—O)P(═S)— or —(—NR)P(═S)—,-   in each of these groups the atom (D) is doubly bonded to the hetero    atom (E), which in turn is bonded to the sulfur atom (S), which is    coupled to the silicon atom (Si) by means of a group (G),-   R¹ mutually independently denotes H,-   a straight, cyclic or branched alkyl chain, preferably (C₁–C₁₈)    alkyl, particularly preferably (C₁–C₄) alkyl,-   optionally alkyl chains containing unsaturated components such as    double bonds (alkenes), triple bonds (alkines) or alkyl aromatics    (aralkyl) or aromatics and having the same meanings as in formula    (II),-   G independently of the other substituents denotes hydrogen, a    straight, cyclic or branched alkyl chain with (C₁–C₁₈), the alkyl    chains can optionally contain an unsaturated component, such as    double bonds (alkenes), triple bonds (alkynes) or alkyl aromatics    (aralkyl) or aromatics,-   if p=0 in formula (IV), G is preferably hydrogen (H),-   G does not correspond to the structure of an α,β-unsaturated    fragment which is bonded to the Y fragment in such a way that an    α,β-unsaturated thiocarbonyl fragment is formed,-   X¹, X² and X³ each mutually independently have the meaning as in    formula (I).

An index p of 0 to 2 is preferred, whereby X¹, X² or X³ is an RO— forexample RC(═O)O—. A fragment where p=0, X¹, X² for example X³=ethoxy andwhere G=alkyl skeleton or substituted alkyl skeleton with C₃ to C₁₂ isparticularly preferred. At least one X need not be equal to —R¹.

In (Q)_(z)D(=E) Q can be oxygen, sulfur or (—NR—), D can be carbon,sulfur, phosphorus or sulfonyl, E can be oxygen, sulfur or (═NR¹).

Preferred examples for the (—YS—) function in formulae (IV) and (V) are:

thiocarboxylate esters —C(═O)—S—, dithiocarboxylates —C(═S)—S—,thiocarbonate esters —O—C(═O)—S—, dithiocarbonate esters —S—C(═O)—S— and—O—C(═S)—S—, trithiocarbonate esters —S—C(═S)—S—, dithiocarbamate esters—N—C(═S)—S—, thiosulfonate esters —S(═O)₂—S—, thiosulfate esters—O—S(═O)₂—S—, thiosulfamate esters (—N—)S(═O)₂—S—, thiosulfinate esters—C—S(═O)—S—, thiosulfite esters —O—S(═O)—S—, thiosulfimate estersN—S(═O)—S—, thiophosphate esters P(═O)(O—)₂(S—), dithiophosphate estersP(═O)(O—)(S—)₂ or P(═S)(O—)₂(S—), trithiophosphate esters P(═O)(S—)₃ orP(═S)(O—)(S—)₂, tetrathiophosphate esters P(═S)(S—)₃, thiophosphamateesters —P(═O)(—N—)(S—), dithiophosphamate esters —P(═S)(—N—)(S—),thiophosphoramidate esters (—N—)P(═O)(O—)(S—), dithiophosphoramidateesters (—N—)P(═O)(S−)₂ or (—N—)P(═S)(O—)(S—) or trithiophosphoramidateesters (—N—)P(═S)(S—)₂.

The following compounds can for example be used as silane having thegeneral formula (IV) or (V):

-   2-triethoxysilyl-1-ethyl thioacetate, 2-trimethoxysilyl-1-ethyl    thioacetate, 2-(methyldimethoxysilyl)-1-ethyl thioacetate,    3-trimethoxysilyl-1-propyl thioacetate, triethoxysilyl methyl    thioacetate, trimethoxysilyl methyl thioacetate, triisopropoxysilyl    methyl thioacetate, methyldiethoxysilyl methyl thioacetate,    methyldimethoxysilyl methyl thioacetate, methyldiisopropoxysilyl    methyl thioacetate, dimethylethoxysilyl methyl thioacetate,    dimethylmethoxysilyl methyl thioacetate, dimethylisopropoxysilyl    methyl thioacetate, 2-triisopropoxysilyl-1-ethyl thioacetate,    2-(methyldiethoxysilyl)-1-ethyl thioacetate,    2-(methyldiisopropoxysilyl)-1-ethyl thioacetate,    2-(dimethylethoxysilyl)-1-ethyl thioacetate,    2-(dimethylmethoxysilyl)-1-ethyl thioacetate,    2-(dimethylisopropoxysilyl)-1-ethyl thioacetate,    3-triethoxysilyl-1-propyl thioacetate, 3-triisopropoxysilyl-1-propyl    thioacetate, 3-methyldiethoxysilyl-1-propyl thioacetate,    3-methyldimethoxysilyl-1-propyl thioacetate,    3-methyldiisopropoxysilyl-1-propyl thioacetate,    1-(2-triethoxysilyl-1-ethyl)-4-thioacetyl cyclohexane,    1-(2-triethoxysilyl-1-ethyl)-3-thioacetyl cyclohexane,    2-triethoxysilyl-5-thioacetyl norbomene,    2-triethoxysilyl-4-thioacetyl norbomene,    2-(2-triethoxysilyl-1-ethyl)-5-thioacetyl norbomene,    2-(2-triethoxysilyl-1-ethyl)-4-thioacetyl norbomene,    1-(1-oxo-2-thia-5-triethoxysilylphenyl benzoic acid,    6-triethoxysilyl-1-hexyl thioacetate, 1-triethoxysilyl-5-hexyl    thioacetate, 8-triethoxysilyl-1-octyl thioacetate,    1-triethoxysilyl-7-octyl thioacetate, 6-triethoxysilyl-1-hexyl    thioacetate, 1-triethoxysilyl-5-octyl thioacetate,    8-trimethoxysilyl-1-octyl thioacetate, 1-trimethoxysilyl-7-octyl    thioacetate, 10-triethoxysilyl-1-decyl thioacetate,    1-triethoxysilyl-9-decyl thioacetate, 1-triethoxysilyl-2-butyl    thioacetate, 1-triethoxysilyl-3-butyl thioacetate,    1-triethoxysilyl-3-methyl-2-butyl thioacetate,    1-triethoxysilyl-3-methyl-3-butyl thioacetate,    3-trimethoxysilyl-1-propyl thiooctoate, 3-triethoxysilyl-1-propyl    thiopalmitate, 3-triethoxysilyl-1-propyl thiooctoate,    3-triethoxysilyl-1-propyl thiobenzoate, 3-triethoxysilyl-1-propyl    thio-2-ethylhexanoate, 3-methyldiacetoxysilyl-1-propyl thioacetate,    3-triacetoxysilyl-1-propyl thioacetate, 2-methyl diacetoxysilyl-    1-ethyl thioacetate, 2-triacetoxysilyl- 1-ethyl thioacetate,    1-methyldiacetoxysilyl-1-ethyl thioacetate or    1-triacetoxysilyl-1-ethyl thioacetate.

An organosilicon compound having the general formula (VI)X¹X²X³Si-A-Sub  (VI)can be used as silane, whereby X¹, X², X³ and A each mutuallyindependently have the meaning according to formula (I) and Sub is —SH,—Cl, −Br, —I, —NH₂, —NH(A-SiX¹X²X³), —N(A-SiX¹X²X³)₂, —N—H—CH₂—CH₂—NH₂,NH—CH₂—CH₂—NH—CH₂—CH₂—NH₂, NHEt, NEt₂, NH(C₄H₉), O—C(O)—CMe═CH₂,O—CH₂—(CH—O—CH₂) (DS glymo) or —SCN.

The following compounds can for example be used as the silane having thegeneral formula (VI):

-   (MeO)₃Si—(CH₂)₃—Cl, (MeO)₃Si—(CH₂)₃—SH, (MeO)₃Si—(CH₂)₃—NH₂,    (MeO)₃Si—(CH₂)₃—SCN,-   (MeO)₃Si—(CH₂)₃—O—C(O)CMe=CH₂, (MeO)₃Si—(CH₂)₃—O—CH₂—(CH—O—CH₂),-   (EtO)₃Si—(CH₂)₃—Cl, (EtO)₃Si—(CH₂)₃—NH₂, (EtO)₃Si—(CH₂)₃—SH,    (EtO)₃Si—(CH₂)₃—SCN,-   (EtO)₃Si—(CH₂)₃—O—C(O)CMe=CH₂, (EtO)₃Si—(CH₂)₃—O—CH₂—(CH—O—CH₂),-   (C₃H₇O)₃Si—(CH₂)₃—Cl, (C₃H₇O)₃Si—(CH₂)₃—SH, (C₃H₇O)₃Si—(CH₂)₃—SCN,-   (C₃H₇O)₃Si—(CH₂)₃—O—C(O)CMe=CH₂ or (C₃H₇O)₃Si—(CH₂)₃—NH₂,    (C₃H₇O)₃Si—(CH₂)₃—O—CH₂—(CH—O—CH₂)

Oligomers of organosilicon compounds having the general formula (I) to(VI) can be used as the silane. The oligomers can be produced byoligomerisation or co-oligomerisation.

Oligomeric silanes are described for example in EP 652 245 B1, EP 0 700951 B1, EP 0 978 525 A2 and DE 199 29 021 A1. Each of these publicationsis incorporated herein by reference.

Mixtures of silanes can also be used as silane compounds for modifyingfillers, for example mixtures of silanes having the general formula I–VIor mixtures of the oligomeric or polymeric siloxanes of silanes havingthe general formula I–VI or mixtures of silanes having the generalformula I–VI with mixtures of the oligomeric or polymeric siloxanes ofsilanes having the general formula I–VI.

A natural and/or synthetic filler can be used as biopolymeric,biooligomeric, oxidic or siliceous filler.

The biopolymeric, biooligomeric, oxidic or siliceous filler can contain—OH or —O acetate, for example —O—C(O)—CH₃, groups at the surface, whichcan react with the reactive groups of the silanes used, preferably theiralkoxy groups.

The biopolymeric, biooligomeric, oxidic or siliceous filler can becompatible with rubbers and display the fine-particle character andreinforcing effect in the polymer matrix that is necessary for this use.

Natural or modified starch, cellulose, amylose, amylopectin, celluloseacetate, maltose, cellobiose, lactose, sucrose, raffinose, glycogen,pectins, chitin or natural or modified proteins can be used asbiopolymeric or biooligomeric filler.

Silicate, for example kaolin, mica, kieselguhr, diatomaceous earth,talc, wollastonite or clay as well as silicates inter alia in the formof glass fibres or glass fabrics can be used as natural siliceousfiller.

Almost all types of oxides, for example aluminium oxide, aluminiumhydroxide or trihydrate, zinc oxide, boron oxides, magnesium oxides ortransition-metal oxides such as titanium dioxide, can be used as oxidicfillers.

Moreover, aluminium silicates, silicates, zeolites, precipitated orpyrogenic silicic acids with BET surface areas (measured with gaseousnitrogen) of 1 to 1000 m²/g, preferably to 300 m²/g, can be used asoxidic or siliceous filler.

By way of example, the precipitated silicic acids sold by Degussa-HülsAG under the trade name Ultrasil (Ultrasil 7000 GR, Ultrasil VN 3,Ultrasil VN 3 GR, Ultrasil VN 2 and Ultrasil VN 2 GR), the Hisil rangeof silicic acids sold by PPG Industries Inc. (Hi-Sil® 195G, Hi-Sil®190G, Hi-Sil® 170G, Hi-Sil® 255G, Hi-Sil® EZ, Hi-Sil® 243LD, Hi-Sil®233, Hi-Sil® 315) and the Zeosil range of products sold by Rhodia, forexample Zeosil 115 Gr, Zeosil 125 Gr, Zeosil 145 Gr, Zeosil 165 Gr,Zeosil 175 Gr, Zeosil 195 Gr, Zeosil 215 Gr, can be used. The same istrue of silicic acids from other manufacturers having similar propertiesfor example product characteristics or analytical data like the silicicacids mentioned above.

Compounds that are gaseous under normal temperature and pressureconditions and are suitable as a carrier fluid for silanes can be usedas compressed gas. Carbon dioxide, helium, nitrogen, dinitrogenmonoxide, sulfur hexafluoride, gaseous alkanes with 1 to 5 C atoms(methane, ethane, propane, n-butane, isobutane, neopentane), gaseousalkenes with 2 to 4 C atoms (ethylene, propylene, butene), gaseousalkines (acetylene, propyne and but-1-yne), gaseous dienes (propadiene),gaseous fluorocarbons, chlorinated hydrocarbons and/orchlorofluorocarbons (freons, CFCs, HCFCs) or substitutes thereof usedbecause of current legislation, or ammonia, and mixtures of thesesubstances, can be used by way of example.

Carbon dioxide can preferably be used as compressed gas since it isnon-toxic, non-combustible, poorly reactive and inexpensive.Furthermore, the necessary supercritical conditions can easily beachieved since the critical pressure and critical temperature are 73 barand 31° C. respectively. The compressed carbon dioxide used ascompressed gas can also have a bacteriostatic effect.

Compressed gases can be defined according to E. Stahl, K. W. Quirin, D.Gerard, “Verdichtete Gase zur Extraktion und Raffination”,Springer-Verlag, page 12–13, incorporated herein by reference.Compressed gases can be supercritical gases, critical gases or gases inthe liquefied region.

The compressed gas is extremely advantageous for this specialapplication. Thanks to the high solubilising power and diffusibility,the low viscosity and the ability to enable in particular silanes orsilane oligomers to have high diffusion rates in the compressed gas, sothat a substance can be deposited in the interstices of the microporoussubstrate, they are extremely suitable for impregnating microporoussolids with monomeric or oligomeric substances. After application thesilanes can be transported by the compressed gas into the pores andchannels of the porous fillers. Furthermore, since compressed gases aregaseous under normal conditions they can easily be separated from thefiller after treatment and in the case of carbon dioxide in particularthey also have virtually no environmentally hazardous potential sincethey disappear into the natural carbon cycle or can easily be recycled.

The compressed gas can be placed under pressure in a chamber orcontainer with an air-tight seal containing the material to be treated.During this process the pressure can be raised, generally fromatmospheric pressure, to the operating pressure of the process accordingto the invention.

First of all the biopolymeric, biooligomeric, oxidic or siliceous fillercan be brought into contact with a liquid consisting of the puresolvent, more precisely the gas that is potentially transformable intothe compressed state, or of a pre-prepared solution of silane in theabove gas, which is subsequently converted to the compressed state. Thiscontact can be established for example in a container or in ahermetically sealed chamber into which the unmodified filler and thesilane-containing gas matrix are introduced. “Establishing contact” canmean that the cited material is immersed in the impregnating liquid andwetted and covered by it, preferably that the biopolymeric,biooligomeric, oxidic or siliceous filler is completely immersed, orthat all external and internal surfaces of the biopolymeric,biooligomeric, oxidic or siliceous filler are in contact with thesilane-containing impregnating liquid.

In the process according to the invention the pressure, which is alsoknown as the operating pressure, can generally be between 1 and 500 bar,preferably between 1 and 400 bar, particularly preferably between 1 and300 bar. These ranges include all specific values and subrangestherebetween, such as 2, 5, 10, 50, 100, 200 and 250 bar.

The temperature (operating temperature) at which the process can beperformed is between 0 and 300° C., preferably between 0 and 200° C.,particularly preferably between 10 and 120° C. These ranges include allspecific values and subranges therebetween, such as 20, 50, 100 and 150°C.

The solubility of the silane in the compressed gas can be dependent onits type, on the pressure and the temperature; it can also be modulatedand optimised, primarily by altering the last two parameters in order toadjust the physical properties of the silane-containing impregnatingmixture. In many cases the concentration of the silane in the solutionused as reaction medium can influence the efficacy of the treatment.

The reaction can be performed in a typical reaction vessel forhigh-temperature/high-pressure reactions or high-pressure extractions.

During the modification the pressure can be kept constant at variouspressure levels for periods of 5–720 min, preferably 5–240 min,particularly preferably 5–30 min, and during this time the filler can beimmersed in the compressed gas, stirred in it or the gas can be passedthrough it.

The biopolymeric, biooligomeric, oxidic or siliceous filler and thesilane can be continuously circulated with a suitable stirring device.The stirring speed can be adjusted to the prevailing temperature and tothe pressure prevailing at that temperature.

A lifting agitator, blade agitator, straight-arm paddle agitator,perforated paddle agitator, cross-arm paddle agitator, anchor agitator,gate agitator, blade roll, propeller agitator, screw mixer, turbineagitator, disc agitator, planetary-type agitator, centrifugal mixer orimpeller agitator can be used as the stirring device.

The stirring device can operate at 1–200 revolutions, strokes orcirculations per minute.

The silanes used can be undissolved, partially dissolved or whollydissolved in the compressed gas.

The biopolymeric, biooligomeric, oxidic or siliceous filler and thesilane can first be thoroughly mixed together or brought into contactand then mixed with the gas in the compressed state.

The biopolymeric, biooligomeric, oxidic or siliceous filler can first bethoroughly mixed or brought into contact with the gas in the compressedstate and only then mixed with the silane.

The silane can first be thoroughly mixed or brought into contact withthe gas in the compressed state and only then mixed with thecorresponding biopolymeric, biooligomeric, oxidic or siliceous filler.

Following the surface modification, the silane-modified biopolymeric,biooligomeric, oxidic or siliceous filler can include an evacuation orrelease stage with separation of the compressed gas from the endproduct.

The evacuation or release stage can be performed in less than 10 min.

The evacuation or release stage can be performed in a time of between 10min and 180 min, preferably between 10 min and 120 min, particularlypreferably between 10 min and 60 min.

The evacuation or release stage can be performed at temperatures ofbetween 1 and 300° C., preferably between 1 and 100° C., particularlypreferably between 50 and 100° C., and most particularly preferably attemperatures of between 70 and 100° C.

The invention also provides rubber compounds wherein they containrubber, the silane-modified biopolymeric, biooligomeric, oxidic orsiliceous filler according to the invention, optionally precipitatedsilicic acid and/or carbon black and/or other rubber auxiliarysubstances.

Natural rubber or synthetic rubbers can be used to produce rubbercompounds according to the invention. Preferred synthetic rubbers aredescribed for example in W. Hofmann, Kautschuktechnologie, GenterVerlag, Stuttgart 1980. They include inter alia polybutadiene (BR),polyisoprene (IR), styrene/butadiene copolymers with styrene contents of1 to 60, preferably 5 to 50 wt. % (E-SBR or S-SBR), isobutylene/isoprenecopolymers (IIR), butadiene/acrylonitrile copolymers with acrylonitrilecontents of 5 to 60, preferably 10 to 50 wt. % (NBR),ethylene/propylene/diene copolymers (EPDM), and mixtures of theserubbers.

The rubber compounds according to the invention can contain additionalrubber auxiliary products, such as e.g. reaction accelerators,retarders, antioxidants, stabilisers, processing aids, plasticisers,waxes, metal oxides and activators, such as triethanolamine,polyethylene glycol or hexanetriol, as well as other rubber auxiliaryproducts known to the rubber industry.

The rubber auxiliary substances can be used in conventional quantities,which depend inter alia on the intended application. Conventionalquantities are for example quantities of 0.1 to 50 wt. % relative torubber.

Sulfur, organic sulfur donors or radical formers can be used ascrosslinkers. The rubber compounds according to the invention can alsocontain vulcanisation accelerators.

Examples of suitable vulcanisation accelerators aremercaptobenzothiazoles, sulfenamides, guanidines, thiurams,dithiocarbamates, thio ureas and thiocarbonates.

The vulcanisation accelerators and crosslinkers can be used inquantities of 0.1 to 10 wt. %, preferably 0.1 to 5 wt. %, relative torubber.

The rubbers can be mixed with the filler according to the invention,optionally with precipitated silicic acid and/or carbon black and/orother rubber auxiliary substances in conventional mixing units, such asrolls, internal mixers and compounding extruders. Such rubber compoundscan conventionally be produced in internal mixers, whereby the rubbers,the filler according to the invention, optionally the precipitatedsilicic acid and/or carbon black and/or other rubber auxiliarysubstances are first incorporated at 100 to 170° C. in one or moresuccessive thermomechanical mixing stages. The sequence and time ofaddition of the individual components can have a critical influence onthe compound properties obtained. The rubber compound thus obtained canthen be combined with the crosslinking chemicals by known means in aninternal mixer or on a roll at 40 to 110° C. and processed into theso-called unvulcanised mix for the subsequent process steps, such asmoulding and vulcanisation for example.

Vulcanization of the rubber compounds according to the invention cantake place at temperatures of 80 to 200° C., preferably 130 to 180° C.,optionally under pressure of 10 to 200 bar.

The rubber compounds according to the invention are suitable for theproduction of moulded parts made from rubber, for example for theproduction of pneumatic tires for cars and lorries, tire treads for carsand lorries, tire components for cars and lorries, such as e.g. sidewall, internal liner and undertread, cable sheaths, tubes, drive belts,conveyor belts, roll coverings, bicycle and motorcycle tires andcomponents thereof, shoe soles, sealing rings, profiles and dampingelements.

In comparison to the purely physical blends, ofbis(3-triethoxysilylpropyl) tetrasulfane with silicic acid for example,such as are known e.g. from U.S. Pat. No. 4,076,550, incorporated hereinby reference, the silane-modified biopolymeric, biooligomeric, oxidic orsiliceous fillers according to the invention display the advantage ofgood storage stability and hence performance stability.

In comparison to the in-situ method that has already been used for yearsin the rubber industry and the untreated filler that this methodrequires, the silane-modified biopolymeric, biooligomeric, oxidic orsiliceous fillers according to the invention have the advantages of alow water content in the treated filler, a low moisture absorbency, anda higher compacted bulk weight and a higher bulk density in comparisonto the untreated filler. Compared to known silane-modified fillers theyare characterised by a better storage stability, better dispersion inrubber and furthermore by better processing characteristics for users inthe rubber-processing industry (homogeneous compounding, fewer mixingstages and shorter mixing times).

Whereas during the mixing process in the in-situ method a chemicalreaction has to be performed in which an optimum process control isrequired, and the silanisation reaction releases considerable amounts ofalcohol, which escape from the compound and lead to problems in theexhaust air, this is avoided by the use of the fillers according to theinvention.

EXAMPLES

Having generally described this invention, a further understanding canbe obtained by reference to certain specific examples which are providedherein for purposes of illustration only and are not intended to belimiting unless otherwise specified.

Examples of the Production of a Filler According to the Invention FillerAccording to the Invention, Example A

1500 g of Ultrasil VN3 are introduced into a drum mixer (4 bafflesmeasuring 7 cm in height). The drum is rotated at a speed of 20 rpm on arolling stand at an incline of 18°. Over 55 min 120 g Si 69 (8 phf) aresprayed in through a 6 cm hole in the cover of the drum using acommercial manual spray pump. The drum is then allowed to run down for 5min.

130 g of the silicic acid pretreated with Si 69 are then introduced intothe 600 ml charge vessel of a high-pressure extraction autoclavepreheated to 70° C. The pressure is slowly raised to 150 bar by pumpingin CO₂. After being allowed to stand for 15 min the temperature israised to 100° C. by heating the jacket of the autoclave. The system iskept constant for one hour at 100° C. and 200 bar. The pressure is thenslowly reduced to 80 bar. Extraction is performed with 1.2 kg CO₂ for 25min at 80 bar and 100° C. Extraction is then performed with 0.5 kg CO₂for 30 min at 300 bar and 80° C. The system is then decompressed and thefinished filler removed.

Filler According to the Invention, Example B

2000 g of Ultrasil VN3 are dried for 2 h in a circulating air oven at105° C. 1500 g of the dried Ultrasil VN3 are introduced into a drummixer (4 baffles measuring 7 cm in height). The drum is rotated at aspeed of 20 rpm on a rolling stand at an incline of 18°. Over 55 min 120g Si 69 (8 phf) are sprayed in through a 6 cm hole in the cover of thedrum using a commercial manual spray pump. The drum is then allowed torun down for 5 min.

130 g of the silicic acid pretreated with Si 69 are then introduced intothe 600 ml charge vessel of a high-pressure extraction autoclavepreheated to 70° C. The pressure is slowly raised to 150 bar by pumpingin CO₂. After being allowed to stand for 15 min the temperature israised to 100° C. by heating the jacket of the autoclave. The system iskept constant for one hour at 100° C. and 200 bar. The pressure is thenslowly reduced to 80 bar. Extraction is performed with 1.2 kg CO₂ for 25min at 80 bar and 100° C. Extraction is then performed with 0.5 kg CO₂for 30 min at 300 bar and 80° C. The system is then decompressed and thefinished filler removed.

Filler According to the Invention, Example C

1650 g of the powder from a precipitated silicic acid Ultrasil VN3 and132 g (8 phf) Si69 are placed in a 15 1 steel autoclave with amagnetically coupled lifting agitator. An internal autoclave pressure of155 bar at a temperature of 90° C. is then established with CO₂ andjacket heating. The mixture is left for 1 hour at 90° C. and 155 bar.The sample is then returned to normal pressure, as a result of which itis cooled. A finely powdered, colourless filler is obtained, which canbe used without special processing.

The residual alcohol (ethanol) on the filler is determined as follows byreference to the procedure described in Kautschuk, Gummi, Kunststoffe51, (1998) 525 von Hunsche et al.:

10 ml diethylene glycol monobutyl ether (DEGMBE) and 0.3 ml 0.5 mol/lH₂SO₄ are added to 1 g of the filler according to the invention in aglass ampoule which after being filled is closed with a tight-fittingcap. The mixture is thoroughly mixed in the glass ampoule for 20 min at60° C. in a water bath. 10 ml decane is then added to the mixture, whichhas quickly been brought to a temperature of 25° C. Appropriate amountsare then removed from the organic phase for HPLC analysis on ethanol(HPLC apparatus with Jasco 851-AS autosampler, Jasco PU 980 pump, 7515ARI detector; TiO₂ column, 250×4.5 mm, 5 μm, YMC.; mobile phase: DEGMBEwith cyclohexane; temperature 25° C.).

It can thus be shown for example that of the original 6 equivalents ofethanol per molecule of Si69 ([(C₂H₅)O]₃Si(CH₂)₃]₂S₄) in the filleraccording to the invention C, only 0.71 equivalents are still present.The silane has bonded to the surface of the silicic acid, releasing 5.29equivalents of ethanol and forming Si—O—Si— bonds with the surface ofthe silicic acid.

The analytical values for the fillers according to the invention areshown in Table 1.

The compacted bulk density is determined according to DIN EN 787-11.

The samples are dried for 15–20 h at 105° C. and the BET surface areadetermined according to DIN 66131 (volumetric method).

The pore maxima for mesopores and macropores can be read off directlyfrom the corresponding diagrams (cumulative intrusion volume (ml/g) orlog differential pore volume (dV/dlog D) for the pore volumedistribution (ml/g) as a function of the pore diameter (μm).

TABLE 1 Starting Known material pre-silanised Pre-silanised silicicPre-silanised silicic Pre-silanised silicic VN3 silicic acid acidaccording to the acid according to the acid according to the Unitsilicic acid VP Coupsil 8108 invention, Example A invention, Example Binvention, Example C Compacted bulk density g/l 210 220 250 260 270 BETsurface area m²/g 178 ± 3  144 ± 3  142 ± 3  130 ± 3  157 ± 3  Mesoporevolume, (d = 2–30 nm) ml/g  0.43 ± 0.03  0.38 ± 0.03  0.40 ± 0.03  0.38± 0.03  0.33 ± 0.03 Mesopore volume, (d = 2–50 nm) ml/g  0.94 ± 0.06 0.73 ± 0.06  0.82 ± 0.06  0.77 ± 0.06  0.69 ± 0.06 Pore maximum, nm 19± 2 23 ± 2 22 ± 2 20 ± 2 19 ± 2 mesopores Macropores, volume, ml/g 2.65± 0.2 2.80 ± 0.2 2.47 ± 0.2 2.43 ± 0.2 2.92 ± 0.2 (d > 30 nm)Macropores, volume, ml/g 2.30 ± 0.1 2.37 ± 0.1 2.06 0.1 2.06 ± 0.1 2.56± 0.2 (d > 50 nm) Pore maximum, nm 2000 ± 200 2700 ± 200 2500 ± 200 2500± 200 20000 ± 2000 macropores Residual ethanol μmol/g  0 390 388 649 137content prod.

The coupling reagent Si 69 is a bis(triethoxysilylpropyl) tetrasulfanefrom Degussa AG. Ultrasil VN3 is a precipitated silicic acid fromDegussa AG with a BET surface area of 170 m²/g. The pre-silanisedsilicic acid VP Coupsil 8108 is obtainable from Degussa AG as anexperimental product. It is a silicic acid that is comparable toUltrasil 7000 GR, with a BET surface area of 175 m²/g, which ispre-silanised with 8% Si 69.

Rubber Compounds

The formulation used for the rubber compounds is given in Table 2 below.The unit phr denotes contents by weight, relative to 100 parts of thecrude rubber used. The general process for producing rubber compoundsand their vulcanisates is described in the following book: “RubberTechnology Handbook”, W. Hofmann, Hanser Verlag 1994, incorporatedherein by reference.

TABLE 2 Compound A/C In-situ Compound D Reference Compound B ReferenceSubstance [phr] [phr] [phr] Stage 1 Buna VSL 5025-1 96 96 96 Buna CB 2430 30 30 Ultrasil 7000 GR 80 — — Pre-silanised silicic — 83 — acidaccording to the invention, example C VP Coupsil 8108 — — 83 ZnO 3 3 3Stearic acid 2 2 2 Naftolen ZD 10 10 10 Vulkanox 4020 1.5 1.5 1.5Protector G35P 1 1 1 Si 69 6.4 — — Stage 2 Batch from stage 1 Stage 3Batch from stage 2 Vulkacit D 2 2 2 Vulkacit CZ 1.5 1.5 1.5 Sulfur 1.51.5 1.5

The polymer VSL 5025-1 is a solution-polymerised SBR copolymer fromBayer AG with a styrene content of 25 wt. % and a butadiene content of75 wt. %. 73% of the butadiene is 1,2-linked, 10% cis-1,4-linked and 17%trans-1,4-linked. The copolymer contains 37.5 phr oil and displays aMooney viscosity (ML 1+4/100° C.) of 50±4.

The polymer Buna CB 24 is a cis-1,4-polybutadiene (neodymium type) fromBayer AG with a cis-1,4 content of 97%, a trans-1,4 content of 2%, a 1,2content of 1% and a Mooney viscosity of 44±5.

Naftolen ZD from Chemetall is used as aromatic oil. Vulkanox 4020 is a6PPD from Bayer AG and Protektor G35P is an anti-ozonant wax fromHB-Fuller GmbH. Vulkacit D (DPG) and Vulkacit CZ (CBS) are commercialproducts from Bayer AG.

Ultrasil 7000 GR is a readily dispersible precipitated silicic acid fromDegussa AG with a BET surface area of 170 m²/g.

The rubber compounds are produced in an internal mixer in accordancewith the mixing instructions in Table 3.

TABLE 3 Stage 1 Settings Mixing unit Werner & Pfleiderer model E Speed60 rpm Ram force 5.5 bar Void volume 1.581 Fill ratio 0.56 Flow temp.70° C. Mixing proc. 0 to 1 min Buna VSL 5025-1 + Buna CB 24 1 to 3 min ½silicic acid or pre-silanised silicic acid, ZnO, stearic acid, NaftolenZD 3 to 4 min ½ silicic acid or pre-silanised silicic acid, antioxidant4 min Clean 4 to 5 min Mix 5 min Clean 5 to 6 min Mix and remove Batchtemp. 145–150° C. Storage 24 h at room temperature Stage 2 SettingsMixing unit As for stage 1 apart from: Speed 70 rpm Flow temp. 70° C.Fill ratio 0.53 Mixing proc. 0 to 2 min Break up batch from stage 1 2 to5 min Maintain batch temperature at 150° C. by varying speed 5 minRemove Batch temp. 150° C. Storage 4 h at room temperature Stage 3Settings Mixing unit As for stage 1 except for Speed 40 rpm Fill ratio0.50 Flow temp. 50° C. Mixing proc. 0 to 2 min Remove batch from stage2, accelerator, sulfur 2 min and sheet out on laboratory mixing rolls(diameter 200 mm, length 450 mm, flow temperature 50° C.) Homogenize:Score 3× on left, 3× on right and fold over and Pass through 8× with anarrow nip (1 mm) and 3× with a wide nip (3.5 mm) Remove sheet. Batchtemp. 85–95° C.The rubber test methods are set out in Table 4.

TABLE 4 Physical test Standard/conditions ML 1 + 4, 100° C., stage 3 DIN53523/3, ISO 667 Cure-meter test, 165° C. DIN 53529/3, ISO 6502Dmax–Dmin [dNm] t10% and t90% [min] Tensile test on ring, 23° C. DIN53504, ISO 37 Tensile strength [MPa] Moduli [MPa] Elongation at break[%] Shore-A hardness, 23° C. [SH] DIN 53 505 Viscoelastic properties,DIN 53 513, ISO 2856 0 and 60° C., 16 Hz, 50 N initial force and 25 Namplitude force Dynamic modulus E* [MPa] Loss factor tan δ[ ] Ballrebound, 23° C., 60° C. [%] ASTM D 5308 DIN abrasion, 10 N force [mm³]DIN 53 516

Example 1

In Example 1 the reference compound (A) mixed in situ with 6.4 phr ofthe coupling reagent Si 69 is compared with compound (B) with thesilane-modified silicic acid according to the invention. Theformulations used for compounds (A) and (B) are set out in Table 2, andthe mixing instructions used are shown in Table 3. The results of therubber tests are set out in Table 5.

TABLE 5 Results for Example 1 Compound (A) (B) ML (1 + 4) [ME] 63 67Dmax–Dmin [dNm] 16.6 18.4 t10% [min] 1.8 1.3 t90% [min] 28.2 31.7Shore-A hardness [SH] 63 61 Tensile strength [MPa] 15.5 15.9 Modulus at100% [MPa] 1.6 1.7 Modulus at 300% [MPa] 7.8 8.4 RF 300%/100% [ ] 4.94.9 Elongation at break [%] 450 440 DIN abrasion [mm³] 77 82 Ballrebound, 60° C. [%] 59 62 E* (0° C.) [MPa] 14.3 14.1 tanδ (0° C.) [ ]0.483 0.461 E* (60° C.) [MPa] 6.4 6.4 tanδ (60° C.) [ ] 0.146 0.144

As can be seen from the data in Table 5, the viscosities ML (1+4) forcompounds (A) and (B) are at a comparable level and the vulcanisationcharacteristics are also similar. The static and dynamic data islikewise comparable within the limits of conventional variations inrubber tests. The identical value for the reinforcing factor RF300%/100% for compounds (A) and (B) indicates an equally high silicicacid-silane bonding. This clearly shows that the use of the silicic acidaccording to the invention leads to rubber properties that arecomparable with those of the in-situ reference.

Example 2

Example 2 shows that the rubber properties obtained by using thecommercial pre-silanised silicic acid VP Coupsil 8108 (D) decline incomparison to the in-situ reference compound (C). Compounds (C) and (D)are based on the formulations given in Table 2. In a change from themixing instructions used in Example 1 and set out in Table 2, in thisexample the first mixing stage is mixed at a speed of 70 rpm and a flowtemperature of 70° C. and the second mixing stage at an initial speed of80 rpm and a flow temperature of 80° C. The results are shown in Table6.

TABLE 6 Results for Example 2 Compound (C) (D) ML (1 + 4) [ME] 60 82Dmax–Dmin [dNm] 18.9 22.1 t10% [min] 1.6 1.1 t90% [min] 23.2 36.0Shore-A hardness [SH] 62 69 Tensile strength [MPa] 13.0 13.0 Modulus at100% [MPa] 1.9 2.3 Modulus at 300% [MPa] 8.9 9.1 RF 300%/100% [ ] 4.74.0 Elongation at break [%] 380 380 DIN abrasion [mm³] 91 88 Ballrebound, 23° C. [%] 32 33 E* (0° C.) [MPa] 15.4 20.5 Tanδ (0° C.) [ ]0.486 0.502 E* (60° C.) [MPa] 6.5 7.7 Tanδ (60° C.) [ ] 0.138 0.144

The values from Table 6 show that the high level of the in-situreference compound is not achieved when the known, pre-silanised silicicacid VP Coupsil 8108 is used. The higher Mooney viscosity, the higherShore-A hardness and the higher dynamic moduli E* all indicate anunsatisfactorily homogeneous silanisation, leading to a higher fillernetwork in compound (D). The reinforcing factor RF 300%/100% forcompound (D) also drops significantly as compared with reference (C).

The advantage of using the silicic acids according to the invention liesin the fact that in contrast to the known use of in-situ silanisationaccording to the prior art with liquid silanes, such as e.g. Si 69,there is no need to perform a chemical reaction, requiring an optimumprocess control, during the mixing process. Furthermore, in the knownin-situ silanisation considerable amounts of alcohol aredisadvantageously released, escaping from the compound and leading toproblems in the exhaust air.

The examples clearly show that the use of the pre-silanised silicicacids according to the invention results in rubber properties comparableto the prior art without causing the disadvantages mentioned above, suchas arise in the known in-situ silanisation. By contrast, although theproblem of ethanol evolution during mixing is avoided with the use ofcommercial pre-silanised silicic acids, such as e.g. VP Coupsil 8108,the good rubber properties of the in-situ reference are not achieved.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

This application is based on German patent application serial No. 101 22269.6, filed on May 8, 2001, and incorporated herein by reference.

1. A silane-modified biopolymeric, biooligomeric, oxidic or siliceousfiller obtained by reacting at least one biopolymeric, biooligomeric,oxidic or siliceous filler in a compressed gas with at least one silane,wherein the compressed gas is a supercritical gas, a critical gas or agas in the liquefied region.
 2. The silane-modified biopolymeric,biooligomeric, oxidic or siliceous filler according to claim 1, whichcontains between 0.1 and 50.0 wt. % silane.
 3. A rubber compound, whichcomprises a rubber and the silane-modified biopolymeric, biooligomeric,oxidic or siliceous filler according to claim
 1. 4. The rubber compoundof claim 3, further comprising precipitated silicic acid and/or carbonblack and/or other rubber auxiliary substances.
 5. A method of producinga molded part, comprising molding the rubber compound of claim 3 into amolded part.
 6. A method of producing an article selected from the groupconsisting of pneumatic tires for cars and lorries, tire treads for carsand lorries, tire components for cars and lorries, cable sheaths, tubes,drive belts, conveyor belts, roll coverings, bicycle and motorcycletires and components thereof, shoe soles, sealing rings, profiles anddamping elements, comprising incorporating the rubber compound of claim3 into the article.